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<h1 class="title toc-ignore">Using Use</h1>



<p>The <code>renv::use()</code> function can make it easier to define
stand-alone R scripts that include their R package requirements directly
in the script itself. For example:</p>
<div class="sourceCode" id="cb1"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="co"># write down the set of packages required by this script</span></span>
<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>renv<span class="sc">::</span><span class="fu">use</span>(</span>
<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>  <span class="st">&quot;digest&quot;</span>,         <span class="co"># use the latest-available version of digest</span></span>
<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a>  <span class="st">&quot;rlang@0.3.4&quot;</span>     <span class="co"># use an older release of rlang (installed from archive)</span></span>
<span id="cb1-5"><a href="#cb1-5" tabindex="-1"></a>)</span>
<span id="cb1-6"><a href="#cb1-6" tabindex="-1"></a></span>
<span id="cb1-7"><a href="#cb1-7" tabindex="-1"></a><span class="co"># use the requested packages</span></span>
<span id="cb1-8"><a href="#cb1-8" tabindex="-1"></a>digest<span class="sc">::</span><span class="fu">digest</span>(<span class="fu">list</span>(<span class="at">answer =</span> <span class="dv">42</span>))</span></code></pre></div>
<p>Running a script with these contents will:</p>
<ol style="list-style-type: decimal">
<li><p>Automatically download the requested packages – in this case, the
latest release of <code>digest</code>, alongside
<code>rlang 0.3.4</code>,</p></li>
<li><p>Install the requested packages (plus their recursive package
dependencies) to a temporary library path,</p></li>
<li><p>Activate that library path, so that it’s used subsequently in the
script.</p></li>
</ol>
<p><code>renv::use()</code> can hence be a useful way of sharing
standalone R scripts with a set of specific package requirements.
Running these scripts will ensure the requested packages are
automatically downloaded and installed.</p>
<p>In addition, you can also supply the path to a lockfile. For
example:</p>
<div class="sourceCode" id="cb2"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="co"># use a particular lockfile in the context of this script</span></span>
<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a>renv<span class="sc">::</span><span class="fu">use</span>(<span class="at">lockfile =</span> <span class="st">&quot;/path/to/renv.lock&quot;</span>)</span>
<span id="cb2-3"><a href="#cb2-3" tabindex="-1"></a></span>
<span id="cb2-4"><a href="#cb2-4" tabindex="-1"></a><span class="co"># the rest of this script will run with the packages as declared</span></span>
<span id="cb2-5"><a href="#cb2-5" tabindex="-1"></a><span class="co"># in that lockfile installed into a temporary library path</span></span></code></pre></div>
<p>This can be useful in projects where you’d like to associate
different lockfiles with different documents – for example, in a <a href="https://bookdown.org/yihui/blogdown/">blog</a> or a website where
you’d like to associate a separate lockfile with each post. Once the
post is complete, you could use
<code>renv::snapshot(lockfile = &quot;/path/to/renv.lock&quot;)</code> to “save”
the state that was active while authoring that lockfile, and then use
<code>renv::use(lockfile = &quot;/path/to/renv.lock&quot;)</code> in that document
to ensure the blog post is always run using that lockfile on future
renders.</p>



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